Question

The trachea and mainstem bronchi: A) constrict violently when their beta-2 receptors are stimulated excessively. B) are approximately 10 to 12 cm in length and are joined together at the hilum. C) do not contain mucous-producing cells in patients without a respiratory disease. D) are lined with beta-2 receptors that result in bronchodilation when stimulated?

1) constrict violently when their beta-2 receptors are stimulated excessively.
2) are approximately 10 to 12 cm in length and are joined together at the hilum.
3) do not contain mucous-producing cells in patients without a respiratory disease.
4) are lined with beta-2 receptors that result in bronchodilation when stimulated.

Answer 1

The trachea and mainstem bronchi have beta-2 receptors that cause bronchodilation when stimulated. This reaction helps regulate airway size and airflow, especially during stress or exercise.

Step-by-step explanation:

The correct answer to the question is D: the trachea and mainstem bronchi are lined with beta-2 receptors that result in bronchodilation when stimulated. Beta-2 receptors, when activated by certain substances like epinephrine, lead to the relaxation of the smooth muscle in the bronchial walls, thus increasing the airway diameter. This process is known as bronchodilation.

Beta-2 receptors play a vital role in regulating airway size and resistance, particularly during times of stress or exercise, where increased airflow is necessary. The other listed options are incorrect: bronchi and trachea constrict in response to parasympathetic stimulation, not sympathetic; they are approximately 10-15 cm in length, not specifically 10 to 12 cm, and all parts of the airway contain mucous-producing cells regardless of the presence of respiratory disease.